1. Field of the Invention
Embodiments relate to technology for converting an analog upstream radio frequency (RF) signal to a digital signal and transmitting the digital signal via an Internet protocol (IP) packet, based on an optical network in a cable broadcasting network.
2. Description of the Related Art
A cable broadcasting network refers to a network configured as a hybrid fiber coaxial (HFC) network, and through which a signal is transferred from a broadcaster to the neighborhood of a customer premises via an optical cable, and the optical signal is converted to an electrical signal in an optical network unit (ONU) and transferred to each customer premises via a coaxial cable. The cable broadcasting network has media characteristics that enable an interactive service such as the Internet using a cable modem and a voice of Internet protocol (VoIP), in addition to a one-way service of transmitting simply a broadcast signal.
Recently, a cable network has evolved into a form in which an optical cable gradually increases to a close neighborhood of a customer premises and a distance of a coaxial cable is minimized, or a form in which the optical cable is directly provided to the customer premises. For example, radio frequency over glass (RFoG) technology simultaneously secures a stability of a broadcasting service and an ultrahigh speed of the Internet by transferring a cable broadcast signal via the optical cable. The RFoG technology may provide an ultrahigh-speed Internet service while maintaining a stable broadcasting quality of a cable television (TV), by transmitting an RF-type real-time cable broadcast signal via an optical cable network, for example, a fiber to the home (FTTH), in lieu of an existing HFC network for a cable broadcast.
A recent cable transmission system applies such an RFoG technology to allow a cable broadcasting network to be connected from a headend to a customer premises via an optical cable. In general, a broadcasting and communication service may be transferred via an RF signal in a cable broadcasting network.
However, the RFoG technology may incur a significant amount of costs for construction. In an RFoG device located on a customer premises, a price of a component of the device used for modulating an upstream RF signal to an optical signal takes a large portion of a total cost for implementing the RFoG device. Such a cost issue may deter the proliferation of the RFoG construction.